<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../../lib/jquery.min.js">
    </script>
    <script type="text/javascript">
        $(document).ready(function () {
            $(".b").click(function () {
                $(".a").slideToggle(8000);
            })
        })
    </script>
</head>
<style type="text/css">
    .a{
        width: 50%;
        height: 333px;
        border: 1px solid red;
    }
</style>
<body>
<div class="a">
 <p>这是内容</p>
</div>
<button class="b" type="button">点击这里</button>

</body>
</html>